VOLCANIC a.
of cinders, tufa, or lava, during volcanic eruptions. -- Volcanic foci, the subterranean centers of volcanic action; the points beneath volcanoes where the causes producing volcanic phenomena are most active. -- Volcanic glass, the vitreous form of lava, produced by sudden cooling; obsidian. See Obsidian. -- Volcani…
YELLOW a.
spot. (a) (Anat.) A small yellowish spot with a central pit, the fovea centralis, in the center of the retina where vision is most accurate. See Eye. (b) (Zoöl.) A small American butterfly (Polites Peckius) of the Skipper family. Its wings are brownish, with a large, irregular, bright yellow spot on each of the hind w…